I have horizontal ridges or bumps on my left thumb and right middle fingernails. may sound trivial but have never had them. should i be concerned?

Usually...: ...Due to a mild trauma to the growth plate of the nail (just under the cuticle) at some point in the past, with the ridge moving along the nail as it grows.

Get checked: Horizontal nail ridges (or Beau’s lines) run across nail & might be signs of diabetes, thyroid disease, kidney disease. They may occur in people who had syphilis or muscles or who had chemotherapy. These should be evaluated.